The present invention relates to a molding apparatus for forming a mold by filling a mold flask with molding sand, allowing a compressed air to pass through the molding sand to consolidate the molding sand on the surface of a pattern plate, and imparting a squeezing action to the whole part of the molding sand in the mold flask.
With conventional molding apparatus, it has been difficult to obtain a mold having a predetermined hardness and the molding condition solely by the squeezing action, particularly when the pattern has a complicated shape.
In order to overcome this problem, there has been proposed and used a molding apparatus having a jolting device arranged to effect a jolt on the mold sand before the squeezing action is imparted. This jolting device, however, produces undesirable vibration and noise to adversely affect the environmental condition. In addition, the molding apparatus itself should have a construction strong enough to withstand the jolt imparted thereto, which results in an increased size of the apparatus and, hence, in a larger scale of the foundation work requiring a huge cost of equipment as a whole.
Another disadvantage is that the molding sand near the pattern surface is not effectively squeezed after the molding sand has been subject to the jolt, so that it becomes necessary to increase the squeezing pressure which requires a more expensive squeezing device of a larger power. The increased squeezing pressure, on the other hand, accelerates the wear of the pattern plate unfavourably.